Trigger circuit



June 27, 1950 J. T. POTTER 2,512,750

TRIGGER c1RcU1T Filed July 7, 1947 A 2 sheets-sheet 1 INVENTOR.

JOHN T. POTTER ABYWMMV AT TORIVEY June 27, 1950 J, T, POTTER 2,512,750

TRIGGER CIRCUIT Filed July '7, 1947 2 Sheets-Sheet 2 INVENTOR.

JOHN T. POTTE R WWW/MM A TTORNEY' Patented June 27, 1950 .-TRIGGER CIRGUIT AfJohn""I'Potter, Sands. Point,-l N Y.

Application Ju1y`7, 1947;S'erial Nol'159=,f421

(Guaso-27) Thenpresent ^invent-.ion `.concerns Y.trigger cir- .cu'its and, 1@in particulan pulse i voperated elec- .tronic trigger circuits.

I The type of ...triggeri .circuit with l which the present invention I,is l concerned nis one a. having 4 two. .stable- .conditions and; Ain` .which-fthe. change .fronrorue stable .conditiomto the other'.niaybbe .b1-ought..aboutbyameans rof-anelectrical-.pulse f-Acom-monptype Vof.. trigger,circuitnomprisesf two electron tubes withsgridseanda plates cross. connected-so.. thanwhen ione vdraws plateacurrent it cuts offathesother. Suchwa zcircuit-`when pulsed cambe arranged.` so that. the platecurrent.shifts back and'forth upon each-pulse butvit-:visstable with eithercplata drawingcurrent. orderI to operatesthisftype ofstrfigger.-circuitA at higherfaand :higher yfrequencies .the value'fof. the-plate; resistor must-beesuccessively reduced. Practical :operaftionfcan be-.obtainedupfto onetmillion'roperation `per.y second or-fsomewhatfmore:witlrrconventional tubes.

The .present invention -concerns Acircuits adaptedrztcvery/highfifrequencyfztriggering. Jilin Ya f'preferre'd .ftorm of .the g-present .sinvention .za multi-grid @electronic .tube .is :connected :z as an amplerz withfitsrplater feeding: a: tunedzfcircut .and rarsourceA of :high .ffrequencye'signals connected to a screened control grid. Arcut=ff biasi'ds'napplidltoianother control grid so that normally no amplification of the high frequency signal takes place`and noramplie'd signal volt- .a-ge fappearssatrithecplate 'Af'rectifieni'suchfas a thermionic diode or crystal rectieriisnconnected between plate --and the :..biasedecontrol grid so that when a signal appears at the plate. it .is rectiie'dand a resulting positivebias isapplied to"'the control 'grid -'To cause ...the circuitrto trigger" "on aAk positive pulse is -appliedl to .fthe control; grid. Whenthepulse is" receivdl'bythe ygrid 'the"cutl"bias"is momentarily cancelled causing the tube to amplify and apply a signal to the rectifier. The resulting biasv from the rectifier holds the grid above cut-off and the tube continues to amplify in one stable mode even when the pulse stops. To reverse the trigger a negative pulse is applied to the grid causing the tube to cut-oli again and return to its initial condition which is the second stable mode. An output pulse may be derived from the rectier current.

One object of the present invention is to provide a method of and means for triggering electronically at very high rates.

Another object is to provide a trigger circuit 5.12 wlsiichI isstable./and Iwhichacan .be turnedtonrvor roff?. in.V an! extremelyeshort interval of time.

i iStill f. another r'vobject is to provide a 1 trigger 4.circuitfinwhich some. of: lthe. limitationsto very .ihigh .speedfztriggeringlhave been removed.

.T-hese and v=other objectsv will'fbefapparentzfrom the detailed description ofmtheeinventionfgiven in'- connection withthe .drawing.

Infthe :drawing: A!

Eig. 1- shows one fform: of .theipresenteinventiom v; Fig.- 2. shows a fmodiied.v formmf the. present invention.

f in' 1='ig..` 1r a multifgridftubef such las pentagrid tube I..- havingra. cathodel 2,.V rst contr-olf gridf3, screenr grid 4,-: second control grid 5,. suppressor gridf. Saandfplate: 1.-. is utilized as .aV trigger tube. .Plate-.1i isconnectedfthrough a tuned circuit consisting. of i-nductance I 0:- tuned by. capacitance, 9 to afsourcefriianode` voltage-8. Screenf 44 is con- .fnected toa V'suitable intermediate ypoint. offvoltage source 8. 'The tuned circuit may be dampedby af-suitablerresistance II fin-orcler to cause oscillationsf-to die outrrapidly whenthel grid is cutfoff bya-negativepulse. A- source fof high frequency .-signalvoltage in the-form-of high frequency'oscil- -latorfA I 2 @isf connectedrto-controls grid 1 5` by `means of.lead.'25. Control @grid 3 is connected to a source of biasthrough= resistor. 23- of 'suicient .-magnitudeto .normallyv cut-off .'plate. current Aso wthat signalv voltage( from a source I 2 is notainplifiiedeandr-henceidoes ,not appear across the tuned circuitfvS-Im -COntrOL-.grid- 3 is falso connected Sto;gridf'resistor. 2 I^whichfcan support-a'vpulse from pulse source I3.connectedwtowgridv?, by 4means of capacitance.' 22. Grid resistor: 2 I :is also in 'series Kwith rectifier I 5' connected -to plate '1 through #capacitancen 16. :Thef rectierrinay :bef anyfsuitable:.high Q frequency? rectifier` Asuch-f as x a Acrystal rectifier yor a-thermionicfdiode as'shown consistring. ofi-plate f' I1 land cathode I`8 i fthe'fl-atteri being heated iby suitable means not shown. T-herectier circuit is completed by shunt resistor 20 connected from plate I'I to ground G and series inductance I9 connected between cathode I8 and grid 3. The function of resistor 29 is to discharge capacitance I6 when the signal is` removed from plate 'l and inductance I9 is to keep high frequency signals from feeding back from plate 'I to grid 3. A utilization means I4 which may be any suitable device for utilizing pulses from the trigger circuit is connected across resistor 2| by means of lead 24.

In operation tube I triggers on upon receipt of a positive pulse from source I3 and off upon receipt of a negative pulse. Initially tube I is amplified signal appears at plate 'I.

3 biased beyond cut-off through resistor 23 and the high frequency signals from source I2 applied to grid are not amplified and little or no high frequency signal appears at plate 1. When a positive pulse from source I3 is received by grid 3 the cut-off bias is over come and the tube becomes operative. This causes it to amplify the high frequency signals from source I2 and the This signal on plate I is rectied by rectifier l5 causing rectied current to flow in resistor 2l in such a direction as to oppose the cut-off bias. This rectified While only two embodiments of the present invention have been shown and described, many modifications will be apparent to those skilled in the art and within the spirit and scope of the appended claims.

What is claimed is:

1. In a trigger circuit, the combination of, a thermionic amplifier including input and output Imeans, a tunedcircuit connected to. said output ,A amplifier, means for applying a pulse to momencurrent voltage drop across resistor 2| serves to' keep the tube conducting even after the actu'` The rectified current drop in resistorf2l alsol forms a pulse which may :be utilized by means I4. In order to shift the trigger back to its initial condition a negative pulse is applied from source I3 causing grid 3 to momentarily cut-olf. When this happens tube I stops amplifying and hence the plate signal quickly dies out removing the source of bias through the rectifier. The original bias through resistor 23 will thenhold the tube cut off in its initial condition which is one of its stable modes. y

Fig. 2 shows a modified form of the present invention. The amplifier 26 may be a suitable high frequency amplifier capable of being controlled by means of a bias applied to it over lead 39 and producing an output across coil 2'I tuned by capacitance 28 and damped by resistance 29. Initially amplifier 2S receives a cut-off bias from battery 43 through resistance 36 and signals from -high frequency source 30 applied over leads 3| and 32` are not amplified and hence do not appear across inductance 2'I. When a positive pulse from pulse source 4I is applied to amplifier 26 through capacitance 40 and over lead 39 the amplifier is unblockedand it amplies signals from source 30 providing signals in the output across inductance 2'I. Inductance 33 coupled to inductance 21 receives an induced Voltage which is applied to rectifier 34. The resulting rectified current is applied over lead 35 across resistor 36 and serves to oppose the bias from battery 43 thereby keeping amplifier 26 in an unblocked state. function until a negative pulse is applied from source 4I which returns the system to its initial condition. An output pulse may be taken off across resistance 36 and applied to a utilization means 42 t0 form a useful output.

This circuit which has been described above is capable of very high frequency triggering. Oscillator I2 may have an output frequency of 100 megacycles or more and with this high frequency excitation tube I may be turned on or off in a period of the order of one ten-millionth of a second or less.

Hence amplifier 26 continues to tarily oppose said bias to provide amplified signals in said tuned circuit, and a rectifier circuit ,connectedbetween said tuned circuit and said bias means to maintain a signal opposed to said bias.

2.` In a trigger circuit as set forth in claim 1, means for utilizing at least a portion of said rectified signal as an outputpulse.

3. In a trigger circuit, the combinationof,v a thermionic amplifier including input and output means, a tuned circuit connected to said output means,'a sourceof 'high frequencyv oscillations connected tosaid input means ,mea'ns vfor apply,- ing a gain-reducing bias 'to saidamplier, means for applying a pulse to momentarily oppose said bias to provide 4amplified high lfrequency signals in said tuned circuit,'"means for rectifying at least a portion of s'aidv amplified signals coupled to said tuned circuit and said bias means to maintain a bias opposed to said galnlreducingbias, and means for` deriving an output pulse from said rectifying means.

4. Ina 'trigger' circuit, the combination of, a

thermionic vacuum tube including at least a con'- trol grid, a screened grid and an anode,'a tuned circuit coupled to said anode,"a lsource of 4high frequency signals connected to said' screened grid', a source o'f negative bias 'connected to said Number f Name 2,010,253 Barton Aug. 6,1935 2,070,900 Harris," Feb., 16, 1937 2,140,350 Dawson Dec. 13, 41938 2,447,057 Crosby,...` Aug. 17 1948 

